The present invention relates generally to a composite image forming apparatus, and more particularly to a composite image forming apparatus in which an image of a document is automatically combined with an image of a character so that a composite image is formed.
Conventionally, the handling of confidential documents is an important matter for companies and public organizations. If a copy of a confidential company document is unlawfully obtained by an outsider, the company may be seriously damaged due to such an in-house secret being leaked. As a measure for preventing the leaking of secrets, a marking (for example, a serial number) is, in advance, added to each copied page of a confidential document by means of an image forming device, and copies of the document are given to the necessary personnel only. Each copied page of the document has a mark added to it that is different from the other added marks.
For example, if a conventional printer having a function for adding to each copied page of a document a page number that is different from the other added page numbers is used, it is possible to insert a page number corresponding to the respective serial number into each of the copied pages, which are copied from a confidential document by means of the conventional printer. However, it is easy to remove the added page numbers from the copies of the document and reproduce a new copy in which the added page numbers are removed. That is, the page number added to each copied page of the document can be easily deleted by correcting the image of the copied page, or by covering a portion of each copied page on which the page number is inserted only, with a white sheet. Thus, in the case in which the above conventional printer is used only, it is impossible to prevent the added page number from being deleted.
Also, there is a conventional image forming device which is capable of overlapping a given pattern, indicating that it is a copy of a confidential document, over the image of a document. If a serial number is added by means of this device to each copies page of the document, the images of the added pattern and the document overlap each other. There is a problem in that the image density of the added pattern or the character size thereof will make it difficult to read or interpret the image of the document. In addition, the above conventional device has a problem in that an operator must perform manual operations for adding a number to each copied page of the document, and considerable time and labor are required when it is necessary to make many copies of the document.